The storage or containment of volatile or toxic fluids has been a safety and environmental concern for numerous years. Underground storage tanks or systems have been used in various industries, e.g., fuel distribution, in attempts to stabilize tanks and reduce potential damage to tanks from external sources. These underground storage tanks, however, have increasingly been criticized for actual and potential environmental problems such as leakage of fluid from the tanks into the ground. Also, the owners of these underground storage tanks have problems in determining whether and when a tank has been damaged. These tanks can additionally be expensive to install and maintain and generally lack mobility.
Above-ground storage tanks have also been developed over the years, but due to the environmental and other problems associated with underground storage tanks these above-ground storage tanks have been increasingly emphasized. As shown in U.S. Pat. No. 5,282,546 by Bauer titled "Composite Above Ground Liquid Storage Vault" and U.S. Pat. No. 5,564,588 by Reese titled "Method And Storage Tank System For Aboveground Storage Of Flammable Liquids," these above-ground storage tanks or systems often include a primary tank or fluid container having at least portions thereof positioned within a secondary tank or fluid container to thereby allow the second container to inhibit leakage of the fluid from the primary container directly into the ground or surrounding surface mounting area. The space between the outer surfaces of the primary tank and the inner surfaces of the secondary tank is often partially or entirely filled with other granular insulating material to provide a protective layer to the primary tank. In other types of related tank systems, the secondary tank can be formed of a concrete material which forms the protective layer. The protective layer, for example, can inhibit damage to the primary tank, can inhibit the initiating of or spreading of a fire associated with the primary tank, and can provide a temperature insulating layer to the primary tank.
As shown in U.S. Pat. No. 5,450,978 by Crisp et al. titled "Environment Compatible Storage Vessel," sand and other non-conductive particulate medium have also been used instead of concrete for the insulating layer and as the sole support for the primary tank when positioned within the secondary tank. Despite the advancements made in the above-ground storage tanks over the years, these tank systems continue to be heavy, not readily portable, and lack effective mobility particularly when the primary tank is encased with concrete. Also, these tank systems can still be expensive to construct and maintain, time consuming to install, shifting and sliding on the sand when transporting or after installation, and ineffective in providing structural support to the primary tank.
Additionally, some applications of these above-ground tank systems do not require a concrete insulating layer. As shown in U.S. Pat. No. 5,197,627 by Disabato et al. titled "Double Walled Storage Tank," the tank systems used for these applications often lack a secondary tank or container and simply use a double-walled structure. Other tanks systems, such as shown in U.S. Pat. No. 5,555,999 by Wilcox titled "Secondary Containment For Aboveground Flammable And Combustible Liquid Storage Tanks" and U.S. Pat. No. 5,346,093 by De Benedittis et al. titled "Liquid Storage System," often partially expose upper portions of the fuel tank to various weather conditions. These at least partially exposed tank systems, however, can create problems associated with harsh weather or environmental conditions, e.g., heat, rain, snow, and can also be ineffective in providing structural support to the primary tank.